DESCRIPTION
The 68C94 quad universal asynchronous receiver/transmitter (QUART) combines four enhanced Philips Semiconductors industry-standard UARTs with an innovative interrupt scheme that can vastly minimize host processor overhead. It is implemented using Philips Semiconductors’ high-speed CMOS process that combines small die size and cost with low power consumption.

FEATURES
• New low overhead interrupt control
• Four Philips Semiconductors industry-standard UARTs
• Eight byte receive FIFO and eight byte transmit FIFO for each UART
• Programmable data format:
    – 5 to 8 data bits plus parity
    – Odd, even, no parity or force parity
    – 1, 1.5 or 2 stop bits programmable in 1/16-bit increments
• Baud rate for the receiver and transmitter selectable from:
    – 23 fixed rates: 50 to 230.4K baud Non-standard rates to 1.0M baud
    – User-defined rates from the programmable counter/timer associated with each of two blocks
    – External 1x or 16x clock
• Parity, framing, and overrun error detection
• False start bit detection
• Line break detection and generation
• Programmable channel mode
    – Normal (full-duplex), automatic echo, local loop back, remote loopback
• Programmable interrupt priorities
• Identification of highest priority interrupt
• Global interrupt register set provides data from interrupting channel
• Vectored interrupts with programmable vector format
• IACKN and DTACKN signals
• Built-in baud rate generator with choice of 18 rates
• Four I/O pins per UART for modem controls, clocks, etc.
• Power down mode
• High-speed CMOS technology
• 52-pin PLCC and 48-pin DIP
• Commercial and industrial temperature ranges available
• On-chip crystal oscillator
• TTL compatible
• Single +5V power supply with low power mode
• Two multifunction programmable 16-bit counter/timers
• 1MHz 16x mode operation
• 30ns data bus release time
• “Watch Dog” timer for each receiver